Timothy C. Willoughby

• An estimate of chemical loads from ground water to the Grand Calumet River and Indiana Harbor Canal, northwestern Indiana
• Chemical stability of wet-deposition samples subsampled daily for one week
• Quality of wet deposition in the Grand Calumet River watershed, northwestern Indiana, April 29, 1997-April 28, 1998
• Quality of wet deposition in the Grand Calumet River watershed, northwestern Indiana, June 30, 1992-August 31, 1993
• Quality of wet deposition in the Grand Calumet River Watershed, Northwestern Indiana, October 17, 1995-November 12, 1996
• Stability of nitrate-ion concentrations in simulated deposition samples used for quality-assurance activities by the U.S. Geological Survey